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Internet of Things Prof. M. Cesana Exam– February 13, 2012 Family Name Given Name Student ID Total Available time: 1 hour 40 minutes Important: use the blank space after each exercise for your answers. E1 E2 E3 Questions Questions OS 1 – Exercise (6 points) A beacon-enabled Personal Area Network is composed of four motes and a PAN Coordinator. Each mote is assigned a slot of 2 [ms] in the GTS which can carry one packet (the GTS has 4 slots in total). The Beacon Interval (BI) is 210 [ms], the CAP is composed of 7 slots, and the motes have the following traffic pattern: • Mote 1, Poisson distributed uplink traffic of parameter λ1 = 1 [p/s] • Mote 2, Poisson distributed uplink traffic of parameter λ2 = 0.01 [p/s] • Mote 3, Poisson distributed uplink traffic of parameter λ3 = 0.1 [p/s] • Mote 4, Deterministic uplink traffic, λ4=1 packet every 2 beacon intervals The four motes and the PAN coordinator have similar hardware featuring the following energy consumption per unit slot: • Esleep = 5 [uJ] • Eidle = 4 [mJ] • Erec = 6 [mJ] • Etx = 7 [mJ] Find out 1. The duty cycle of the network 2. The average energy consumption of the four motes. 3. The average energy consumption for the PAN Coordinator. 2– Exercise (6 points) A Personal Area Network (PAN) is composed of a PAN Coordinator and 2 motes. The motes are characterized by the following traffic pattern: • Mote 1 generates packets deterministically with intensity λ2=0.01 [pkt/s] • Mote 2 generates packets deterministically with intensity λ2=0.2 [pkt/s] The communication is performed through a token-based access mechanism. The PAN Coordinator polls serially the two devices (starting from Mote 1) and then (after polling both devices) goes to sleep for 5 [s]. If the polled device has a packet to deliver it sends it, otherwise it…